There is no way Google doesn't use fingerprinting, or something even more advanced/creepy. I never sign into Google, use private browsing by default and use VPNs (not to hide, just for various location reasons), and Youtube's recommended for you is full of stuff unrelated the current video I'm watching that I've seen before with different IPs and locations/VPNs. Edit: LMAO at the sudden attempt to bury this post with…
Funnily enough, it wouldn't occur to me however to use my own experience to make a sweeping judgement about what Google does in the large, because I just don't know. Even if I suspected, I'd be loath to confuse this with knowledge for the sake of my own cognitive hygiene.